The major function of disposable absorbent products, such as diapers, training pants, adult incontinence devices, sanitary napkins, panty liners, and the like, is to absorb and contain body exudates. Although these absorbent articles may be highly efficient for the absorption of liquids, they also can create an occlusive micro-environment in the body regions where they are worn. This occlusion micro-environment often results in overhydration of the skin. It is known that overhydrated skin is more susceptible to skin disorders, including erythema (i.e., redness), diaper rash or diaper dermatitis, heat rash, abrasion, pressure marks and skin barrier break-down. Diaper rash is a common form of irritation and inflammation of those parts of an infant's body normally covered by a diaper, which is caused by one or more of the following factors: moisture, occlusion, chafing, continued contact with urine, feces, or both, or mechanical or chemical irritation (see 21 C.F.R. 333.503). When absorbent articles are worn to absorb and contain the body exudates, the skin under the absorbent articles is held in direct contact with body exudates and other irritants, under an occluded condition. Often, the skin is subjected to such condition for extended periods of time, that is, until the soiled article is changed. As the skin under the absorbent article becomes overhydrated or irritated by such prolonged and repeated exposures, the skin condition is compromised, i.e., the skin becomes more susceptible to skin disorders or damages. While this condition is best known in infants, it is not limited to infants. Similar conditions occur with, for example, incontinent or bed-ridden adults.
To address the concerns of skin abnormalities associated with wearing absorbent articles, the practical approaches often attempt to address multiple causes or important cofactors. Reducing skin overhydration by frequent changing of diapers, the use of moisture absorbing powders, the use of superabsorbent materials, and the improvement of air flow in diapers are some of the well known approaches.
A typical approach is to apply a topical cream, ointment, lotion or paste by hand to the buttocks, genitals, anal and/or other regions before placing the absorbent article on the wearer. This procedure usually provides some degree of physical barrier protection to the skin against direct contact with urine, feces or other irritants. However, the barrier approach may be occlusive in itself. It has been found that occlusive barrier material may interfere with the healing and repair of skin's natural barrier function once skin barrier function is compromised or skin disorders have developed.
It is recognized that a skin care composition for skin disorders associated with skin overhydration should have good barrier properties. Petrolatum is a well known barrier protectant which forms a water repellant layer on the skin surface and minimizes moisture loss from the skin. Petrolatum also forms a barrier against large molecules (e.g., fecal enzymes) and particulate matters in body exudates. But this petrolatum layer over skin is occlusive such that it may interfere with the barrier repair capability of the skin. Lanolin is another good barrier protectant as well as a nourishing substance, but lanolin is also occlusive. Many other fats and oils derived from natural sources, such as plants or animals, have been shown to have nourishing and/or occlusive properties, but they often are oxidatively unstable and require hydrogenation or stabilizers. However, hydrogenation tends to increase the viscosity of the substance and reduce its spreadability, and stabilizers may cause other skin problems, such as irritation or allergy.
Another well known barrier substance derived from nature is "vernix caseosa" or "vernix caevsa" (hereinafter "vernix"), which is the substance that covers the entire body of human and mammalian fetuses at or near full term. Vernix on fetal skin exhibits some unique characteristics not found in fully developed or mature skin. It has been shown that vernix has a very low transepidermal water loss (TEWL) value. It is believed that vernix helps the new born infant maintain body temperature by reducing water loss, which is accompanied by heat loss, from the epidernis. Vernix is also a very effective barrier against moisture penetration. Mature skin becomes overhydrated and develops maceration or irritant dermatitis after just a couple of days' exposure to water. In contrast, the full or near term fetus' skin is healthy, smooth and supple, even though is has been exposed to the total immersion environment in the uterus for an extended period of time. Moreover, vernix is a naturally occurring substance that has none of the side effects such as irritation, sensitization and allergy.
Various skin creams, lotions and ointments are available for treating skin disorders. Most of them are moisturizing preparations that enhance water retention in the skin, and thus, are not effective for skin disorders associated with overhydration, such as erythema or diaper rash. However, skin preparations for overhydration problem have been focused mostly on the barrier approach. Hence these preparations tend to be occlusive and hinder the natural barrier repair function of the skin. Moreover, the lotions, creams or ointments have always been applied by hand to the targeted areas. The topical application by hands tends to leave a thick sticky coating or a layer of white residue that is aesthetically unpleasing. This procedure is also wasteful, messy, time-consuming and often forgotten.
Attempts have also been made to prepare absorbent articles which contain a transferable skin care composition on the skin-capacity surface so that the hand-application procedure is not necessary. However, many lotions, creams and ointments generally are not suitable for delivery via an absorbent article because they are fluid or substantially mobile at room temperature. These fluid and mobile substances do not remain localized on the surface of the article but instead may migrate into the interior of the article. Accordingly, these substances can interfere with the absorbency of the interior core layer of the article due to their hydrophobic, barrier properties.
Also a higher level of such compositions must be applied to the article surface in order to provide enough transfer to the skin to achieve a protective coating. This higher add-on level not only increases the cost per article, but also increases the possibility of migration into and through the packaging or wrapper materials, creating an article that smears and leaks greasy substances.
U.S. Pat. No. 4,760,096 to Sakai et al. teaches a moisturizing skin composition comprising a phosphatide (such as lecithin) and one or more C10-C30 carboxylic acid sterol esters. Such compositions preferably contain a caprylic/capric acid triglyceride for enhanced moisturization. A major disadvantage of the composition disclosed by Sakai is that the composition is a moisturizer which enhances the water retention in the skin. Accordingly, it does not prevent or minimize the overhydration problem of the skin under an absorbent article.
U.S. Pat. No. 5,409,903 to Polak et al. teaches a method and a composition for treatment or prevention of skin rash or dermatitis wherein urease containing bacteria, bacterial components and by-products are implicated. The composition may be applied to skin in combination with an adhesive, film-forming or barrier compound. A major disadvantage of Polak et al. is that a thin film coating is required to achieve water vapor or gas permeability, and the composition is only effective as a barrier against enzymes or large particulate materials.
U.S. Pat. No. 3,896,807 to Buchalter teaches an skin-contacting article impregnated with a solid oil phase of a cream formulation which forms a cream upon addition of moisture thereto. A major disadvantage of the article disclosed by Buchalter is that the substance is an occlusive barrier protectant. Another disadvantage of Buchalter is that the transfer of a beneficial substance from the article to the skin is delayed until fluids are absorbed by the solid oil phase.
U.S. Pat. No. 3,489,148 to Duncan et al. teaches a disposable diaper comprising a "hydrophobic and oleophobic" topsheet wherein a portion of the topsheet is coated with a discontinuous film of oleaginous substance. A major disadvantage of the of the diaper disclosed by Duncan et al. is that the hydrophobic and oleophobic topsheet is slow in promoting transfer of urine to the underlying absorbent core.
U.S. Pat. No. 5,643,588 to Roe et al. teaches an absorbent article having a skin treating composition on the surface of a disposable diaper that is solid or semi-solid at ambient temperature, and is transferable to the wearer's skin by contact, wearer motion and/or body heat. However, some of the compositions disclosed by Roe et al. may be occlusive.
In light of the foregoing, it would be desirable to have an article-deliverable skin care composition that is breathable or non-occlusive. Such a skin care composition should also have good barrier properties against urine, feces, or other body exudates or irritants. Such composition should also minimize skin overhydration, maintain the integrity of skin barrier function, and thus effectively prevent secondary irritation or infection when skin is compromised or damaged, and promote the barrier repair function of the skin.
Moreover, it would be desirable that the skin care composition can be immobilized on an absorbent article for hands-free transfer to the wearer's skin during use, for minimizing adverse effects on the absorbency of the article, and for avoiding stains on clothing, bedding or packaging.
It would also be desirable for the skin care composition not to irritate or sensitize the skin and be oxidatively stable for long shelf life of the product.
It would be further desirable to have an absorbent article having a breathable, barrier type skin care composition disposed thereon for hands-free transfer to the wearer's skin by contact, normal wearer motion and/or body heat.
It would also be desirable to have an absorbent article having one or more types of skin care composition disposed thereon, wherein at least a portion of the composition is transferable to the wearer's skin to provide desired skin benefits including a prevention and/or reduction in erythema, a reduction in BM adherence to the skin for easier removal of BM, reduction in occlusion, overhydration and/or abrasion of the skin, and the like.
It would also be desirable to have a skin care composition which is solid or semi-solid at ambient temperature so that it is immobilized on the surface of an absorbent article. The skin care composition should be able to become fluid or plastic at or near skin temperature, or when slight force is applied, so that it is readily transferable to the skin. The skin care composition should also be substantially flowable at the processing temperature so that it can be successfully applied to the article surface, i.e., without tearing or otherwise damaging the article.